<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <style>
        .a{
            background-color: lightblue;
        }
        .b{
            background-color: lightgoldenrodyellow;
        }
    </style>
    <title>replace</title>
</head>
<body>
<div id="box" class="a">
    <p>你好</p>
    <p>你好</p>
    <p>你好</p>
    <p>你好</p>
</div>
<div id="box2" class="b">
    <p>你好</p>
    <p>你好</p>
    <p>你好</p>
    <p>你好</p>
</div>
<script src="JsForReplace.js"></script>
</body>
</html>